Evidence that Saturn's collapsing magnetic tail causes auroras

May 19, 2014

Images of Saturn's northern UV auroras obtained by Nichols and coworkers using the Advanced Camera for Surveys onboard the Hubble Space Telescope. The auroras are clearly visible near the north pole and exhibit changes in shape over the course of the observing interval. Credit: NASA, ESA, Jonathan Nichols (University of Leicester

University of Leicester researchers have captured stunning images of Saturn's auroras as the planet's magnetic field is battered by charged particles from the Sun.

The team's findings provide a "smoking gun" for the theory that Saturn's auroral displays are often caused by the dramatic collapse of its "magnetic tail".

Just like comets, planets such as Saturn and the Earth have a "tail" – known as the magnetotail – that is made up of electrified gas from the Sun and flows out in the planet's wake.

When a particularly strong burst of particles from the Sun hits Saturn, it can cause the magnetotail to collapse, with the ensuing disturbance of the planet's magnetic field resulting in spectacular auroral displays. A very similar process happens here on Earth.

University of Leicester scientists observed this process happening on Saturn firsthand between April and May of 2013 as part of a three-year-long Hubble observing campaign. Their findings have been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.

The ultraviolet images, taken by Hubble's super-sensitive Advanced Camera for Surveys, capture moments when Saturn's magnetic field is affected by bursts of particles streaming out from the Sun.

Due to the composition of Saturn's atmosphere, its auroras shine brightly in the ultraviolet range of the electromagnetic spectrum. This observation campaign using Hubble meant the astronomers were able to gather an unprecedented record of the planet's auroral activity.

The team caught Saturn during a very dynamic light show. Some of the bursts of light seen shooting around Saturn's polar regions travelled at over three times faster than the speed of the gas giant's rotation.

"These images are spectacular and dynamic, because the auroras are jumping around so quickly," Dr Jonathan Nichols, of the University of Leicester's Department of Physics and Astronomy, who led the Hubble observations, said.

"The key difference about this work is that it is the first time the Hubble has been able to see the northern auroras so clearly.

"The particular pattern of auroras that we saw relates to the collapsing of the magnetotail," he added. "We have always suspected this was what also happens on Saturn. This evidence really strengthens the argument."

"Our observations show a burst of auroras that are moving very, very quickly across the polar region of the planet. We can see that the magnetotail is undergoing huge turmoil and reconfiguration, caused by buffering from solar wind," Nichols said. "It's the smoking gun that shows us that the tail is collapsing."

The new images also formed part of a joint observing campaign between Hubble and NASA's Cassini spacecraft, which is currently in orbit around Saturn itself.

Between them, the two spacecraft managed to capture a 360-degree view of the planet's aurora at both the north and south poles. Cassini also used optical imaging to delve into the rainbow of colours seen in Saturn's light shows.

On Earth, observers of auroras see green curtains of light with flaming scarlet tops. Cassini's imaging cameras reveal similar auroral veils on Saturn, which are red at the bottom and violet at the top.

Related Stories

(Phys.org) —NASA trained several pairs of eyes on Saturn as the planet put on a dancing light show at its poles. While NASA's Hubble Space Telescope, orbiting around Earth, was able to observe the northern ...

(PhysOrg.com) -- An international team of scientists led by Dr Jonathan Nichols of the University of Leicester has discovered that Saturn’s aurora, an ethereal ultraviolet glow which illuminates Saturn’s ...

(PhysOrg.com) -- Since the NASA / ESA Cassini-Huygens spacecraft arrived at Saturn in 2004, astronomers and space scientists have been able to study the ringed planet and its moons in great detail. Now, for ...

Several days after Rosetta's close flyby of comet 67P/Churyumov-Gerasimenko on 14 February 2015, images taken on this day by OSIRIS, the scientific imaging system on board, have now been downlinked to Earth. ...

Like coins, most comet have both heads and tails. Occasionally, during a close passage of the Sun, a comet's head will be greatly diminished yet still retain a classic cometary outline. Rarely are we left ...

This week marked the completion of an important step on the path to spacecraft assembly, test, and launch operations for the Origins Spectral Interpretation Resource Identification Security Regolith Explorer ...

NASA's Dawn spacecraft has returned new images captured on approach to its historic orbit insertion at the dwarf planet Ceres. Dawn will be the first mission to successfully visit a dwarf planet when it enters ...

User comments : 1

Wag the Saturn? The problem with this theoretical work is here is no experimentation backing it up, no reference to the scientist who is largely responsible for much of what we know about aurora. Here is a good start...http://hal.archiv...C408.pdf

Please sign in to add a comment.
Registration is free, and takes less than a minute.
Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.

Javascript is currently disabled in your web browser. For full site functionality, it is necessary to enable Javascript.
In order to enable it, please see these instructions.